1. Field
Aspects of the present disclosure relate generally to wireless communication systems, and more particularly, to performing random access procedures.
2. Background
Wireless communication networks are widely deployed to provide various communication services such as voice, video, packet data, messaging, broadcast, etc. These wireless networks may be multiple-access networks capable of supporting multiple users by sharing the available network resources. Examples of such multiple-access networks include Code Division Multiple Access (CDMA) networks, Time Division Multiple Access (TDMA) networks, Frequency Division Multiple Access (FDMA) networks, Orthogonal FDMA (OFDMA) networks, and Single-Carrier FDMA (SC-FDMA) networks. In addition, such networks can conform to one or more network specifications, such as third generation partnership project (3GPP), 3GPP long term evolution (LTE), and/or the like.
A wireless communication network may include a number of evolved Node Bs (referred herein to as eNodeBs or eNBs) that can support communication for a number of user equipments (UEs). A UE may communicate with an eNodeB via the downlink and uplink. The downlink (or forward link) refers to the communication link from the eNodeB to the UE, and the uplink (or reverse link) refers to the communication link from the UE to the eNodeB.
Some wireless communication networks support carrier aggregation (CA) for a UE. In such configurations, the UE can simultaneously communicate with one or more eNodeBs over multiple downlink and/or uplink carriers to improve data throughput. One of the multiple carriers can be designated as a primary component carrier (PCC) over which certain control data or other high priority data can be communicated regarding the PCC and one or more of the other carriers (e.g., secondary component carriers (SCC)). Previous configurations allowed uplink communications only on the PCC, and thus timing adjustment (TA) could be accomplished over the single PCC with respect to the downlink over the PCC or other carriers. Allowing uplink communications over multiple carriers, however, can lead to TA considerations for each of the carriers.